Mold base



I'. T. QUARNsTRoM MOLD BASE Filed June 9, 1944 April 15 1947.

INVENTOR. /m/P @MwST/MM BY v Patented Apr. 15,` 1947 UNITED STATES PATENT oFFIcE MOLD BASE Y Ivar T. Quarnstrom, Detroit, Mich.

Application June 9, 1944, Serial No.f539,516

(Cl. 18e-42) 8 Claims.

This invention relates to a standard mold base for injection plastic molding, and has for its principal object the elimination of dowel and leader pins where possible for providing a simplified structure.

It is the further object herein to eliminate the ejector plate push back pins heretoore provisioned centrally within the mold, and substitute combination leader and push back pins which also act as guides for ejector plate movements. to provide bush- It is the further object herein ings for said combination push back pins which also function as dowels in maintaining an immovable relation between the rear cavity plate and its supporting back up plate.

It is the further object herein to eliminate protruding dowel pins from the rear cavity plate. Maximum working area is made possible by placing thecombination push back and leader pins directlyunder the front cavity plate leader pins.

Other objects will be seen from the following specification and claims disclosing the various lelements of the invention and their combinations as illustrated in the accompanying drawing of which- Fig. 1 is a broken away partially sectioned ele` vational view of the mold base; and

Fig. 2 is a plan view thereof with members I6 and 2t removed.

It will be understood that the said drawing illustrates merely a preferable embodiment of the invention, and that other embodiments are contemplated within the scope of the claims hereunder set out.

In the drawing, Fig. 1 shows the standard mold base having a rectangular anchor plate II with two upright parallel members I2 and I3 disposed and secured thereon in spaced relation as shown in detail in Fig. 2. Anchor plate I I is adapted to be secured to and reciprocably carried by the movable member of a conventional molding machine.

A bac-k up plate I4 rectangular in shape is positioned upon the'top edges of members I2 and I3 providing means for supporting the removable and interchangeable rear cavity retainer plate I5. A corresponding front cavity retainer plate I6 is provided similar in shape to said rear cavity plate for compressive cooperative engagement with respect thereto. Both the upper surface I'I of retainer plate I5 and the lower surface IB of retainer plate It are initially blank, but are adapted to have impressed or cut therein, or inserted therein, corresponding and mating `cores andmolds 36 and 31 respectively Within which is 2 injected a plastic material to be molded therein.

Members I I, I2, I4 and I5 are all rmly secured together by screws I9 provisioned through members II, I2 and I4 and threaded into rear cavity plate I5. Also members II, 43, I4 and I5 are secured together by similar screws I9 provisioned through members I I, I3 and I4 and threaded into rear cavityv plate I5, whereby a single compact movable unit is formed.

On the other hand stationary anchor plate 20 adapted to be supported within the stationary part of a molding machine, has provisioned thereunder front cavity retainer plate I5 immovably retained by screws 2|. Thus the stationary molding unit is provided with respect to which the rst described molding unit is reciprocably movable.

It will be noted axially aligned with as shown in Fig. 2.

The four spacedfbushings 22are provisioned through back up plate I4 with their annular flanged upper portions 23 extending partially above said plate. Flanged portions 23 extend up into and are securely nested within corresponding Vopenings in the rear cavity retainer plate I5 whereby an immovable relationship is established between back up plate I4 and rear cavity retainer plate I5.

Corresponding bushings 24 are oppositely pro- `visioned within rear cavity retainer plate I5 with their openings aligned with the openings of bushings 22. The annularly flanged portions 25 of bushings 24 are in engagement with flanged portions 23 of bushings 22 as shown in Fig. 1.

Four leader pins 26 retained within front cavity plate I6 extend downwardly therefrom for sliding engagement within corresponding bushings 24 when the cavity plate I5 is projected into engagement with the stationary cavity plate I6 for the molding operation.

Said leader pins function to obtain proper alignment between said cavity plates and the molds provisioned therein. Ejector plate 21 with its ends outwardly flanged at 28 is longitudinally disposed between parallel members I2 and I3 and is adapted ior relative reciprocable movement between anchor plate II and back up plate I4. Ejector pins 28 attached to ejector plate 21 extend upwardly therefrom and through back up plate I4 and also into openings within mold core 36 provisioned within cavity plate I5. A corresponding mold 3l is oppositely provisioned within cavity plate I6 for cooperation with core 36 in forming the molded member.

that the four screws I9 are the four screws 2l positioned Plate 29 secured upon ejector plate 21 retains and secures in upright position' combination push back and leader pins 30. With ejector plate 21 inoperative said pins are slidingly and guidingly provisioned within bushings 22.

After the molding operation rear cavity plate l is withdrawn by operation of the molding machine. Ejector plate is withdrawn only partially and then is stopped from further movement by stationary bar 3B extending from the molding machine and loosely through anchor plate Il. Movement of cavity plate l5 and back up plate I4 relative to said retained ejector plate and ejector pins 2S' is guided by leader pins 3i! within bushings 22 and 24.

By operation of the molding machine and in anticipation or the next molding operation, the rear cavity plate l5, as well as members lli, I3, I2 and l l, are projected towards front cavity plate i6 so that initially the push back pins SS are operatively engaged by the ends of leader pins 26. Furthergmovement of cavity plate I5 up to engagement with cavity plate I6 thus eiects relative return of push back pins 39 and ejector plate 2'? to their initial inoperative positions.

Thus push back pins perform the additional function of leader pins relatively to the members l5 and i4 heretofore employed separately.

In operation in carrying out injection molding, the cavity retainer plate l 5 is brought tightly into cooperative engagement with the stationary cavity retainer plate 6, and a plastic molding material is injected through locator 3l and nozzle 32 indicated in Fig. 1.

It Will be noted that ejector plate 21 is initially maintained adjacent but in spaced relation to anchor plate H by means of studs 33 with their central projectionsd being seated in corresponding openings 35 in anchor plate Il. Having described my invention reference should now be had to the claims which follow for determining the scope thereof.

I claim:

1. In a mold base employing front and rear cavity plates, a reciprocal anchor plate, upright parallel members secured thereon in spaced relation, a back-up plate for said rear cavity plate carried by said parallel members, a stationary anchor plate for supporting said front cavity plate, an ejector plate reciprocally mounted `between said parallel members, a plurality of upright push-back pins extending from said ejector plate through said back up plate and into said rear cavity plate for relative reciprocal sliding engagement within corresponding openings in said back-up plate and rear Ycavity plate, and. a plurality of aligned oppositely disposed leader pins depending from said front cavity plate and extending into said rear cavity plate for relative reciprocal engagement within the same openings in said rear cavity plate and of such length that they operatively abut said push-back pins when the mold is closed to return said ejector plate to its linoperative position.

2. In a mold base employing front and rear cav" y plates, a reciprocal anchor plate, `upright parallel members secured thereon in spaced relation, a back-up pla-te for said rear cavity plate carried by said parallel members, a stationary anchor plate for supporting said front cavity plate, an ejector 'plate reciprocally mounted between said parallel members, a plurality of aligned bushings projecting into said back-up plate and said rear cavity plate, a plurality of upright push-back pins ex-tending from said ejector plate through said back-up plate and into said rear cavity plate for relative reciprocal sliding engagement within said bushings, and a plurality or" aligned oppositely disposed leader pins depending from said front cavity plate and extending into said rear cavity plate for reciprocal engagement Within said bushings, and 0f Such length that they operatively abut said push-back pinswhen the mold is closed to return said ejector plate to its inoperative position,

3. In a mold base employing iront and rear cavity plates, a reciprocal anchor plate, upright parallel members secured thereon in spaced relation, a back-up plate for said rear cavity plate carried by said parallel members, a stationary anchor plate for supporting said front cavity plate, an ejector plate reciprocally mounted between said parallel members, a plurality of bushings projecting through said back-up plate and extending partially into said rear cavity plate, a plurality of aligned bushings within said rear cavity plate, a VpluralityV of upright push-back pins extending Afrom said ejector plate through said back-up plate and into said rear cavity plate for relative reciprocal sliding engagement within said bushings, and a plurality of aligned oppositely disposed leader pins depending from said front cavity plate and extending into said rear cavity plate for relative reciprocal movement within said rear cavity plate bushings, and of such length that they operatively abut said pushback pins when the mold is closed to return said ejector plate to its inoperative position.

4.In a mold base employing front and rear cavity plates, a reciprocal Yanchor plate, upright parallel members secured thereon in spaced relation, a back-up plate for said rear cavity plate carried by said parallel members, a stationary anchor plate for supporting saidfront cavity plate, an ejector plate reciprocally mounted between said parallel members, a plurality of shoulder bushings projecting Within said back-up plate with their shoulders extending into said rear cavity plate, for preventing relative transverse movement of said back-up plate and rear cavity platea plurality of aligned shoulder bushings within said rear cavity plate, a plurality of upright push-back pins extending from said ejector plate through said back-up plate and into said rear `cavity plate for relative reciprocal sliding engagement Within said bushings, and a plurality of aligned .oppositely disposed leader pins depending from said frontcavity plate and extending into said rear cavity plate for relative reciprocal movement therein, and Vof such length that they operatively abut said push-back pins when the mold is closed to return said ejector plate to its inoperativev position.

5. In a mold base employing front and rear cavity plates, a reciprocal anchor plate, upright parallel members secured thereon in spaced relation, a back-up plate for said rear cavity plate carried by said parallel members, a stationary anchor plate for supporting said front cavity plate, an ejector plate reciprocally mounted be tween said parallel members, a plurality of upright push-back pins extending from said ejector plate through said back-up plate and into said rear cavity plate for relative reciprocal sliding engagement within corresponding openings in said back-up plate and rear cavity plate, a plurality of aligned oppositely disposed leader pins depending from said front cavity plate extending into said rear cavity plate for relative reciprocal engagement Within the same openings in said rear cavity plate, and of such length that they operatively abut said push-back pins when the mold is closed to return said ejector plate to its inoperative position, and a plurality of screws projecting through said reciprocal anchor plate, said parallel members, said back-up plate, and threaded into said rear cavity plate.

6. In a mold base employing front and rear cavity plates, a reciprocal anchor plate providing a support for said rear cavityT plate, a stationary anchor plate for supporting said front cavity plate, an ejector plate reciprocally mounted within said reciprocal anchor plate, a plurality of upright ejector plate push-back pins extending from said ejector plate and into said rear cavity plate for relative reciprocal sliding movement therein, and a plurality of aligned oppositely disposed leader pins depending from said front cavity plate and extending into said rear cavity plate for relative reciprocal movement therein, and of such length that they operatively abut said pushback pins when the mold is closed to return said ejector plate to its inoperativerposition.

7. In a mold cavity plates, a reciprocal anchor plate, upright parallel members secured thereon in spaced relation, a back-up plate for said rear cavity plate carried by said parallel members, a stationary anchor plate for supporting said front cavityv plate, an ejector plate reciprocally mounted between said parallelv members, a plurality of rbush-- ings projecting within said back-up plate and extending into said rear cavity plate, for preventing relative transverse movement of said back-up plate and rear cavity plate, a plurality of aligned bushings within said rear cavity plate,`

a plurality of upright push-back pins extending from said vejector plate through said back-up plate and into said rear cavity plate for relative reciprocal sliding engagement within lsaid bushings, and a pluralityof aligned oppositely disbase employing front and rear posed leader pins depending from said front cav= ity plate and extending into said rear cavity plate for relative reciprocal movement therein, and of such length that they operatively abut said pushback pins when the mold is closed to return said ejector plate to its inoperative position.

8. In a mold base employing front and rear cavity plates, a reciprocal anchor plate, upright parallel members secured thereon in spaced relation, a back-up plate for said rear cavity plate carried by said parallel members, a stationary anchor plate for supporting said front cavity plate, an ejector plate reciprocally'mounted between said parallel members, a plurality of bushings projecting within said back-up plate and extending into said rear cavity plate, for preventing relative transverse movement of said back-up plate and rear cavity plate, a plurality of upright push-back pins extendingv from said ejector plate through said back-up plateand into said rear cavity plate for relative reciprocal sliding engagement within said bushings, and a plurality of aligned oppositely disposed leader pins depending from said front cavity plate and extending into said rear cavity plate for relative reciprocal movement therein, and of such length that they operatively abut said push-back pins when the mold is closed to return said ejector plate to its inoperative position.

WAR T. QUARNSTROM.

REFERENCES CITED The following references are of record in the iile ofrths patent:

UNITED STATES PATENTS Name Date Matson July 14, 1936 Marsh Sept. 28 1943 MacLagan et al. Feb. 10, 1942 Number 

